Calorie needs vary from person to person. This will depend on a huge number of factors, this is where one size fits all approach such as Slimming World and Weightwatchers fall down because they have an inability to tailor for an individual's needs.
Your calorie needs are dependant on the following-
Your exercise- i.e the duration, format and intensity
Your occupation- Are you someone who is sat at a desk or are you someone that is active during your job?
Genetics- Some people naturally burn more calories than others